Ethylxanthoylthioxy-n, n-diethylamino-methyl-phosphine oxide



Patented Feb. 9, 1954 UNITED STATES ETHYLXANTHOYLTHIOXY-N,N-DIETHYL-AMINO-METHYL-PHOSPHINE OXIDE Henry Tolkmith, Midland, Mich., assignor toThe Dow Chemical Company, Midland, Mich., a

corporation of Delaware No Drawing. Application April 21, 1953, SerialNo. 350,235

This compound is a viscous oil, somewhat soluble in many organicsolvents and substantially insoluble in water. It is of value as anintermediate for the preparation of more complete phosphorus derivativesand as a toxic constituent of parasiticide compositions.

The new compound may be prepared by reacting one molecular proportion ofan alkali metal ethylxanthate with one molecular pro portion ofN,N-diethylamidomethanephosphonic chloride of the formula C2115 li/CHa-P in an inert organic solvent such as benzene. f the alkali metalxanthates found useful in the reaction, it is preferred to employ thesodium compound.

In carrying out the reaction, the sodium ethylxanthate andN,N-diethylamidomethanephosphonic chloride are dispersed in the solventand the resulting mixture heated for a period of time at a temperatureof from 40 to 80 C. As the desired product has a tendency to decomposeat temperatures in excess of 80 C., temperatures substantially in excessof 80 C. for any appreciable period of time should be avoided. Uponcompletion of the reaction, the mixture may be filtered and the filtratedistilled under reduced pressure at gradually increasing temperatures upto a temperature of 80 C. to separate low boiling constituents and toobtain as a residue the desired ethylxanthoylthioxy N,Ndiethylaminomethyl-phosphine oxide.

The N,N diethylamidomethanephosphonic chloride employed as a startingmaterial in the above-described process may be prepared by reacting onemolecular proportion of diethylamine with at least two molecularproportions of methanephosphonic dichloride in an inert organic solventsuch as diethyl ether. The reaction is carried out in the presence of ahydrogen chloride acceptor, which may conveniently be an excess of theamine reactant. The reaction takes place readily at temperatures of from20 to 40 C. In carrying out the reaction, the diethylamine is addedportionwise to the methanephosphonic dichloride dispersed in the solventand the resulting mixture heated for a period of time to complete thereaction. The reaction is somewhat exothermic, temperature beingcontrolled by regulation of the rate of contacting the reactants, aswell as by the addition and subtraction of heat, if required. Uponcompletion of the reaction, the mixture may be filtered and the filtratefractionally distilled under reduced pressure to separate the desiredN,N-diethylarnidomethanephosphonic chloride. The latter is an oilyliquid having a boiling point of 135 C. at 27 millimeters pressure.

In a representative preparation, '7 grams (0.049 mole) of sodiumethylxanthate was added to 7.5 grams (0.044; mole) ofN,N-diethylamidomethanephosphonic chloride dispersed in 50 millilitersof benzene and the resulting mixture heated for 2 hours at a temperatureof C. The mixture was then filtered and the filtrate concentrated bydistillation under reduced pressure to a temperature up to 60 C. toobtain as a residue an ethylxanthoylthioxy N,Ndiethylaminomethyl-phosphine oxide product. The latter is a viscous oilhaving a density of 1.189 at 20 C.

The new ethylxanthoylthioxy N,N diethyla1nino-methyl-phosphone oxideproduct is effective as a parasiticide and adapted to be employed forthe control of a Wide range of agricultural and household pests such asflies, mites, aphids, beetles and cockroaches. For such use, thecompound may be dispersed on an inert finely divided solid and employedas a dust. Also, such mixtures may be dispersed in water with the aid ofa dispersing and wetting agent and the resulting aqueous suspensionsemployed as sprays. In other procedures, the new product may be employedin oils, as a constituent in oil-in-water emulsions, or in waterdispersion with or without the addition of emulsifying, wetting ordispersing agents. Suitable concentrations or the toxicant in dusts arein the order of from about 0.1 to 10 percent by weight of the dust andin liquid suspensions from about 0.1 to 3 pounds per gallons of thespray mixture.

In representative operations against flies and cockroaches, 100 percentkills of these pests are obtained with dust compositions containing 4.5percent by weight of the toxic phosphine oxide.

This is a continuation in part of my copending application Serial No.203,763, filed December 30, 1950.

I claim:

Ethylxanthoylthioxy N,N diethylamino methyl-phosphine oxide.

HENRY TOLKMITI-I.

No references cited.

